The present invention relates to an installation for applying a layer of a corrosion-inhibiting material to internal surface regions of cavities in a metal structure, such as a car body, by flood coating.
In FRG AS No. 27 55 947 of Apr. 24, 1980, there is described an installation for applying a layer of a waxy, corrosion-inhibiting material by flood coating. This installation offers the advantage, as compared to other processes and installations such as the dip coating process, that only the desired surface zones of the cavities are supplied with the material directly and in an excess. In contrast to conventional spray nozzles, this supply takes place without a preferential direction of the movement of material, whereby, as is known, shading effects are evoked which lead precisely at critical locations to a deficient application of material.
In the installation previously proposed, for example, an automobile body is placed on vertically supported zones of the free ends of conduits in such a way that openings in the cavities to be coated are in alignment with the free ends of the conduits. Flood coating consists in filling the cavities through these conduits with the waxy material. The excess material must then be allowed to drain away. This must be done quickly because, among other reasons, there could be the danger of solidification of also the excess waxy material due to cooling of the body. Drainage must be effected through the openings in the cavities in alignment with the free ends of the conduits.
Conceivably, for a rapid evacuation of these openings in the cavities, the zones of the free ends of the feed conduits for the material could be mounted to be retractable or pivotable. However, this results in additional expenditure, not only with respect to the mechanical fastening of these end zones, but also with respect to control, since this movement of the end zones of the conduits must understandably be carried out in synchronism with other procedures during the treatment, for example in proper time sequence with the turning on and turning off of the conveying means for the waxy material or with the activation of a transport mechanism for the article provided with the cavities, i.e. in the present example the automobile body.